Abstract

Background

In recent years, several oral antidiabetic drugs with new mechanisms of action have
become available, expanding the number of treatment options. Sodium/glucose cotransporter-2
(SGLT2) inhibitors are a new class of oral antidiabetic drugs with an insulin-independent
mechanism promoting urinary glucose excretion. We report the results of a combined
Phase 2 and 3 clinical study (Japic CTI-101349) of the SGLT2 inhibitor tofogliflozin
(CSG452, RG7201) in Japanese patients with type 2 diabetes mellitus.

Methods

The efficacy and safety of tofogliflozin were assessed in this multicenter, placebo-controlled,
randomized, double-blind parallel-group study involving 230 patients with type 2 diabetes
mellitus with inadequate glycemic control on diet/exercise therapy. Between 30 October
2010 and 28 February 2012, patients at 33 centers were randomized to either placebo
(n = 56) or tofogliflozin (10, 20, or 40 mg; n = 58 each) orally, once daily for 24
weeks. The primary efficacy endpoint was the change from baseline in HbA1c at week 24.

Results

Overall, 229 patients were included in the full analysis set (placebo: n = 56; tofogliflozin
10 mg: n = 57; tofogliflozin 20 and 40 mg: n = 58 each). The least squares (LS) mean
change (95% confidence interval) from baseline in HbA1c at week 24 was −0.028% (−0.192 to 0.137) in the placebo group, compared with −0.797%
(−0.960 to −0.634) in the tofogliflozin 10 mg group, −1.017% (−1.178 to −0.856) in
the tofogliflozin 20 mg group, and −0.870% (−1.031 to −0.709) in the tofogliflozin
40 mg group (p < 0.0001 for the LS mean differences in all tofogliflozin groups vs
placebo). There were also prominent decreases in fasting blood glucose, 2-h postprandial
glucose, and body weight in all tofogliflozin groups compared with the placebo group.
The main adverse events were hyperketonemia, ketonuria, and pollakiuria. The incidence
of hypoglycemia was low. Furthermore, most adverse events were classified as mild
or moderate in severity.

Conclusions

Tofogliflozin 10, 20, or 40 mg administered once daily as monotherapy significantly
decreased HbA1c and body weight, and was generally well tolerated in Japanese patients with type
2 diabetes mellitus. Phase 3 studies were recently completed and support the findings
of this combined Phase 2 and 3 study.

Trial registration

This study was registered in the JAPIC clinical trials registry (ID: Japic CTI-101349).